1. Field of the Disclosure
This disclosure relates generally to apparatus and methods that use a liner and reaming bit for drilling wellbores.
2. Background Art
Oil wells (also referred to as “wellbores”) are drilled with a drill string that includes a tubular member having a drilling assembly with a drill bit at its bottom end. The tubular member is generally either a jointed pipe or coiled tubing. After the well or a section of the wellbore has been drilled, it is lined with a casing (also referred to as the liner). However, sometimes the liner is placed outside a portion of the drill string and may include a second drill bit, referred to as the reamer drill bit or reamer, above or uphole of the drill bit at the drilling assembly bottom (also referred to as the “pilot” drill bit). The pilot drill bit drills a bore with a certain diameter and the reamer enlarges this bore to the desired wellbore diameter.
It is often desirable to selectively engage and disengage the reamer from the drill string so that the drill string can be retrieved from the wellbore and redeployed without retrieving the reamer or the liner. In the above-noted drilling assembly configuration, the reamer may be placed meters above the pilot drill bit. However, it is often desired to place the reamer relatively close to the pilot drill bit so as to more effectively steer the drilling direction.
The disclosure herein provides improved apparatus and methods for drilling wellbores with a drill string that includes a reamer and a liner.